<template>
  <div>
    <div id="chart">
      <apexchart
        type="bar"
        height="420"
        ref="chart"
        :options="chartOptions"
        :series="series"
      ></apexchart>
    </div>

    <div class="explanation">
      A "bar chart race": each tick re-sorts the entities by value and updates
      the chart. The bars slide to their new ranks and the left-hand category
      labels ride along with them (automatic whenever a reorder update runs with
      <code>dynamicAnimation</code> enabled). The value labels also ride each
      bar and count up/down, via the opt-in <code>dataLabels.animate</code> and
      <code>dataLabels.countUp</code> flags: together these complete the race.
    </div>
  </div>
</template>

<script>
import VueApexCharts from 'vue-apexcharts'

var raceEntities = [
  'United States', 'China', 'Germany', 'Japan', 'France',
  'United Kingdom', 'India', 'Brazil', 'Canada', 'Italy'
]

// A fixed color per country. With distributed bars the color is applied by bar
// POSITION, but this is a race where the bars re-sort every tick, so raceFrame()
// re-orders this palette to match the current ranking below. That keeps each
// country's color stable as it rides up and down the ranks.
var raceColors = {
  'United States': '#3B82F6',
  'China': '#EF4444',
  'Germany': '#F59E0B',
  'Japan': '#10B981',
  'France': '#8B5CF6',
  'United Kingdom': '#EC4899',
  'India': '#14B8A6',
  'Brazil': '#F97316',
  'Canada': '#6366F1',
  'Italy': '#84CC16'
}

// A flag emoji per country, prepended to its axis label by
// yaxis.labels.formatter. SVG axis labels are plain text, so an emoji is the
// simplest way to put an icon in front of a label (real image flags would need
// custom DOM work). Emoji flags render on most platforms; a few Windows
// browsers show the two-letter country code instead.
var raceFlags = {
  'United States': '🇺🇸',
  'China': '🇨🇳',
  'Germany': '🇩🇪',
  'Japan': '🇯🇵',
  'France': '🇫🇷',
  'United Kingdom': '🇬🇧',
  'India': '🇮🇳',
  'Brazil': '🇧🇷',
  'Canada': '🇨🇦',
  'Italy': '🇮🇹'
}

// Persistent value per entity, nudged a little each tick so ranks swap
// gradually (a smooth race rather than a random shuffle).
var raceValues = {}
raceEntities.forEach(function (name, i) {
  raceValues[name] = 300 + (raceEntities.length - i) * 90
})

function raceFrame() {
  raceEntities.forEach(function (name) {
    raceValues[name] = Math.max(
      50,
      raceValues[name] + (Math.random() - 0.45) * 220
    )
  })
  var ranked = raceEntities
    .map(function (name) {
      return { name: name, value: Math.round(raceValues[name]) }
    })
    .sort(function (a, b) {
      return b.value - a.value
    })
  return {
    categories: ranked.map(function (r) { return r.name }),
    data: ranked.map(function (r) { return r.value }),
    // Colors follow the ranking so each country keeps its own color (see above).
    colors: ranked.map(function (r) { return raceColors[r.name] })
  }
}

var raceInitial = raceFrame()

export default {
components: {
apexchart: VueApexCharts,
},
data: function () {
return {
series: [{
  name: 'Value',
  data: raceInitial.data
}],
chartOptions: {
chart: {
  id: 'horizontal-bar-race',
  type: 'bar',
  height: 420,
  animations: {
    dynamicAnimation: {
      speed: 800
    }
  },
  toolbar: {
    show: false
  }
},
plotOptions: {
  bar: {
    borderRadius: 4,
    borderRadiusApplication: 'end',
    horizontal: true,
    // Each bar gets its own color, taken from the `colors` palette by position.
    distributed: true
  }
},
colors: raceInitial.colors,
dataLabels: {
  enabled: true,
  // Opt-in race polish: the value labels ride to each bar's new rank and
  // count up/down from their previous value on every tick.
  animate: {
    enabled: true
  },
  countUp: {
    enabled: true
  }
},
title: {
  text: 'Bar Chart Race',
  align: 'left'
},
xaxis: {
  categories: raceInitial.categories
},
yaxis: {
  labels: {
    // Prepend each country's flag emoji to its axis label.
    formatter: function (val) {
      return (raceFlags[val] || '') + '  ' + val
    }
  }
},
legend: {
  show: false
}
},
}
},
mounted: function () {
  var me = this
  window.setInterval(function () {
    var frame = raceFrame()
    me.$refs.chart.updateOptions({
      series: [{ data: frame.data }],
      xaxis: { categories: frame.categories },
      colors: frame.colors
    })
  }, 1200)
},,
}
</script>

<style>
#chart {
  max-width: 650px;
  margin: 35px auto;
}
.explanation {
  max-width: 620px;
  margin: 0 auto 12px;
  font-size: 13px;
  color: #777;
}
</style>